AOP流程
在doCreateBean()的地方留有AOP的入口
try {
//ioc di，依赖注入的核心方法，
populateBean(beanName, mbd, instanceWrapper);
//bean 实例化+ioc依赖注入完以后的调用，
exposedObject = initializeBean(beanName, exposedObject, mbd);
}
这个方法里面进行AOP的入口的地方
exposedObject = initializeBean(beanName, exposedObject, mbd);
if (mbd == null || !mbd.isSynthetic()) {
//这个地方可能生出代理实例，是aop的入口
wrappedBean = applyBeanPostProcessorsAfterInitialization(wrappedBean, beanName);
}
这里Spring对bd进行代理
进入到AbstractAutowireCapableBeanFactory类中的方法
@Override
public Object applyBeanPostProcessorsAfterInitialization(Object existingBean, String beanName)
throws BeansException {
Object result = existingBean;
for (BeanPostProcessor processor : getBeanPostProcessors()) {
Object current = processor.postProcessAfterInitialization(result, beanName);
if (current == null) {
return result;
}
result = current;
}
return result;
}
这里是spring的埋点操作，然后查看实现类AbstractAutoProxyCreator的具体逻辑
@Override
public Object postProcessAfterInitialization(@Nullable Object bean, String beanName) {
if (bean != null) {
Object cacheKey = getCacheKey(bean.getClass(), beanName);
if (this.earlyProxyReferences.remove(cacheKey) != bean) {
// 这里进入
return wrapIfNecessary(bean, beanName, cacheKey);
}
}
return bean;
}
这里没什么主要逻辑，继续跟进，来到类AbstractAutoProxyCreator的wrapIfNecessary方法中
protected Object wrapIfNecessary(Object bean, String beanName, Object cacheKey) {
if (StringUtils.hasLength(beanName) && this.targetSourcedBeans.contains(beanName)) {
return bean;
}
if (Boolean.FALSE.equals(this.advisedBeans.get(cacheKey))) {
return bean;
}
if (isInfrastructureClass(bean.getClass()) || shouldSkip(bean.getClass(), beanName)) {
this.advisedBeans.put(cacheKey, Boolean.FALSE);
return bean;
}
//创建当前bean的代理，如果这个bean有advice的话
// Create proxy if we have advice.
Object[] specificInterceptors = getAdvicesAndAdvisorsForBean(bean.getClass(), beanName, null);
//如果有切面，则生成该bean的代理
if (specificInterceptors != DO_NOT_PROXY) {
this.advisedBeans.put(cacheKey, Boolean.TRUE);
//把被代理对象bean实例封装到SingletonTargetSource对象中
Object proxy = createProxy(
bean.getClass(), beanName, specificInterceptors, new SingletonTargetSource(bean));
this.proxyTypes.put(cacheKey, proxy.getClass());
return proxy;
}
this.advisedBeans.put(cacheKey, Boolean.FALSE);
return bean;
}
这里有两个重要的逻辑，一个是对于AOP注解的收集，并且封装成Advisor,然后另一个是对收集到的信息进行代理
Advisor的收集
首先是这段代码完成了advisor的收集
Object[] specificInterceptors = getAdvicesAndAdvisorsForBean(bean.getClass(), beanName, null);
这是一个抽象方法，所以要查看他子类具体的实现
@Nullable
protected abstract Object[] getAdvicesAndAdvisorsForBean(Class<?> beanClass, String beanName,
@Nullable TargetSource customTargetSource) throws BeansException;
来到子类AbstractAdvisorAutoProxyCreator中
@Override
@Nullable
protected Object[] getAdvicesAndAdvisorsForBean(
Class<?> beanClass, String beanName, @Nullable TargetSource targetSource) {
//找到合格的切面
List<Advisor> advisors = findEligibleAdvisors(beanClass, beanName);
if (advisors.isEmpty()) {
return DO_NOT_PROXY;
}
return advisors.toArray();
}
可以看到findEligibleAdvisors的返回值是List，所以，具体的实现就是在这里，跟进去继续查看
protected List<Advisor> findEligibleAdvisors(Class<?> beanClass, String beanName) {
//找到候选的切面,其实就是一个寻找有@Aspectj注解的过程，把工程中所有有这个注解的类封装成Advisor返回
// 调用子类的方法AnnotationAwareAspectJAutoProxyCreator
List<Advisor> candidateAdvisors = findCandidateAdvisors();
//判断候选的切面是否作用在当前beanClass上面，就是一个匹配过程。。现在就是一个匹配
List<Advisor> eligibleAdvisors = findAdvisorsThatCanApply(candidateAdvisors, beanClass, beanName);
//针对@Aspect注解切面添加了一个默认的切面 DefaultPointcutAdvisor
extendAdvisors(eligibleAdvisors);
if (!eligibleAdvisors.isEmpty()) {
//对有@Order@Priority进行排序
eligibleAdvisors = sortAdvisors(eligibleAdvisors);
}
return eligibleAdvisors;
}
这里的逻辑较多，首先查看收集的方法
findCandidateAdvisors的实现逻辑
查看子类AnnotationAwareAspectJAutoProxyCreator的具体实现
@Override
protected List<Advisor> findCandidateAdvisors() {
// Add all the Spring advisors found according to superclass rules.
//找到所有的Advisor
List<Advisor> advisors = super.findCandidateAdvisors();
// Build Advisors for all AspectJ aspects in the bean factory.
//主要看这里，创建候选的切面 对@Aspect注解的类进行处理
if (this.aspectJAdvisorsBuilder != null) {
advisors.addAll(this.aspectJAdvisorsBuilder.buildAspectJAdvisors());
}
return advisors;
}
首先调用父类去寻找所有的自定义的advisor
List<Advisor> advisors = super.findCandidateAdvisors();
然后下面的方法是对@Aspect封装
advisors.addAll(this.aspectJAdvisorsBuilder.buildAspectJAdvisors());
所以查看this.aspectJAdvisorsBuilder.buildAspectJAdvisors()方法
public List<Advisor> buildAspectJAdvisors() {
List<String> aspectNames = this.aspectBeanNames;
if (aspectNames == null) {
synchronized (this) {
aspectNames = this.aspectBeanNames;
if (aspectNames == null) {
List<Advisor> advisors = new ArrayList<>();
aspectNames = new ArrayList<>();
//获取spring容器中的所有bean的名称BeanName
String[] beanNames = BeanFactoryUtils.beanNamesForTypeIncludingAncestors(
this.beanFactory, Object.class, true, false);
for (String beanName : beanNames) {
if (!isEligibleBean(beanName)) {
continue;
}
// We must be careful not to instantiate beans eagerly as in this case they
// would be cached by the Spring container but would not have been weaved.
Class<?> beanType = this.beanFactory.getType(beanName);
if (beanType == null) {
continue;
}
//判断类上是否有@Aspect注解
if (this.advisorFactory.isAspect(beanType)) {
aspectNames.add(beanName);
AspectMetadata amd = new AspectMetadata(beanType, beanName);
if (amd.getAjType().getPerClause().getKind() == PerClauseKind.SINGLETON) {
//创建获取有@Aspect注解类的实例工厂，负责获取有@Aspect注解类的实例
MetadataAwareAspectInstanceFactory factory =
new BeanFactoryAspectInstanceFactory(this.beanFactory, beanName);
//创建切面advisor对象
List<Advisor> classAdvisors = this.advisorFactory.getAdvisors(factory);
if (this.beanFactory.isSingleton(beanName)) {
this.advisorsCache.put(beanName, classAdvisors);
}
else {
this.aspectFactoryCache.put(beanName, factory);
}
advisors.addAll(classAdvisors);
}
else {
// Per target or per this.
if (this.beanFactory.isSingleton(beanName)) {
throw new IllegalArgumentException("Bean with name '" + beanName +
"' is a singleton, but aspect instantiation model is not singleton");
}
MetadataAwareAspectInstanceFactory factory =
new PrototypeAspectInstanceFactory(this.beanFactory, beanName);
this.aspectFactoryCache.put(beanName, factory);
advisors.addAll(this.advisorFactory.getAdvisors(factory));
}
}
}
this.aspectBeanNames = aspectNames;
return advisors;
}
}
}
if (aspectNames.isEmpty()) {
return Collections.emptyList();
}
List<Advisor> advisors = new ArrayList<>();
for (String aspectName : aspectNames) {
List<Advisor> cachedAdvisors = this.advisorsCache.get(aspectName);
if (cachedAdvisors != null) {
advisors.addAll(cachedAdvisors);
}
else {
MetadataAwareAspectInstanceFactory factory = this.aspectFactoryCache.get(aspectName);
advisors.addAll(this.advisorFactory.getAdvisors(factory));
}
}
return advisors;
}
首先是这里的逻辑，从Spring容器中找到所有bean的beanname，然后spring的标准操作foreach循环遍历每一个bean
String[] beanNames = BeanFactoryUtils.beanNamesForTypeIncludingAncestors(this.beanFactory, Object.class, true, false);
然后会进行判断是不是类上有@Aspect注解，如果有的话，基本都会进入到getAdvisors这个环节
List<Advisor> classAdvisors = this.advisorFactory.getAdvisors(factory);
这里进行创建切面advisor对象
@Override
public List<Advisor> getAdvisors(MetadataAwareAspectInstanceFactory aspectInstanceFactory) {
//从工厂中获取有@Aspect注解的类Class
Class<?> aspectClass = aspectInstanceFactory.getAspectMetadata().getAspectClass();
//从工厂中获取有@Aspect注解的类的名称
String aspectName = aspectInstanceFactory.getAspectMetadata().getAspectName();
validate(aspectClass);
//创建工厂的装饰类，获取实例只会获取一次
// We need to wrap the MetadataAwareAspectInstanceFactory with a decorator
// so that it will only instantiate once.
MetadataAwareAspectInstanceFactory lazySingletonAspectInstanceFactory =
new LazySingletonAspectInstanceFactoryDecorator(aspectInstanceFactory);
List<Advisor> advisors = new ArrayList<>();
//这里循环没有@Pointcut注解的方法
for (Method method : getAdvisorMethods(aspectClass)) {
// Prior to Spring Framework 5.2.7, advisors.size() was supplied as the declarationOrderInAspect
// to getAdvisor(...) to represent the "current position" in the declared methods list.
// However, since Java 7 the "current position" is not valid since the JDK no longer
// returns declared methods in the order in which they are declared in the source code.
// Thus, we now hard code the declarationOrderInAspect to 0 for all advice methods
// discovered via reflection in order to support reliable advice ordering across JVM launches.
// Specifically, a value of 0 aligns with the default value used in
// AspectJPrecedenceComparator.getAspectDeclarationOrder(Advisor).
Advisor advisor = getAdvisor(method, lazySingletonAspectInstanceFactory, 0, aspectName);
if (advisor != null) {
advisors.add(advisor);
}
}
// If it's a per target aspect, emit the dummy instantiating aspect.
if (!advisors.isEmpty() && lazySingletonAspectInstanceFactory.getAspectMetadata().isLazilyInstantiated()) {
Advisor instantiationAdvisor = new SyntheticInstantiationAdvisor(lazySingletonAspectInstanceFactory);
advisors.add(0, instantiationAdvisor);
}
//判断属性上是否有引介注解
// Find introduction fields.
for (Field field : aspectClass.getDeclaredFields()) {
//判断属性上是否有DeclareParents注解，如果有返回切面
Advisor advisor = getDeclareParentsAdvisor(field);
if (advisor != null) {
advisors.add(advisor);
}
}
return advisors;
}
这里是新建Advisor
Advisor advisor = getAdvisor(method, lazySingletonAspectInstanceFactory, 0, aspectName);
具体实现的逻辑在这里
/*
* candidateAdviceMethod 候选的Advice方法，候选的增强方法
* */
@Override
@Nullable
public Advisor getAdvisor(Method candidateAdviceMethod, MetadataAwareAspectInstanceFactory aspectInstanceFactory,
int declarationOrderInAspect, String aspectName) {
validate(aspectInstanceFactory.getAspectMetadata().getAspectClass());
//获取pointCut对象，最重要的是从注解中获取表达式
AspectJExpressionPointcut expressionPointcut = getPointcut(
candidateAdviceMethod, aspectInstanceFactory.getAspectMetadata().getAspectClass());
if (expressionPointcut == null) {
return null;
}
//创建Advisor切面类，这才是真正的切面类，一个切面类里面肯定要有1、pointCut 2、advice
//这里pointCut是expressionPointcut， advice 增强方法是 candidateAdviceMethod
return new InstantiationModelAwarePointcutAdvisorImpl(expressionPointcut, candidateAdviceMethod,
this, aspectInstanceFactory, declarationOrderInAspect, aspectName);
}
获取pointCut对象，最重要的是从注解中获取表达式
//获取pointCut对象，最重要的是从注解中获取表达式
AspectJExpressionPointcut expressionPointcut = getPointcut(
candidateAdviceMethod, aspectInstanceFactory.getAspectMetadata().getAspectClass());
@Nullable
private AspectJExpressionPointcut getPointcut(Method candidateAdviceMethod, Class<?> candidateAspectClass) {
//从候选的增强方法里面 candidateAdviceMethod 找有有注解
//Pointcut.class, Around.class, Before.class, After.class, AfterReturning.class, AfterThrowing.class
//并把注解信息封装成AspectJAnnotation对象
AspectJAnnotation<?> aspectJAnnotation =
AbstractAspectJAdvisorFactory.findAspectJAnnotationOnMethod(candidateAdviceMethod);
if (aspectJAnnotation == null) {
return null;
}
//创建一个PointCut类，并且把前面从注解里面解析的表达式设置进去
AspectJExpressionPointcut ajexp =
new AspectJExpressionPointcut(candidateAspectClass, new String[0], new Class<?>[0]);
ajexp.setExpression(aspectJAnnotation.getPointcutExpression());
if (this.beanFactory != null) {
ajexp.setBeanFactory(this.beanFactory);
}
return ajexp;
}
这里扫描对象然后封装成AspectJAnnotation对象
//从候选的增强方法里面 candidateAdviceMethod 找有有注解
//Pointcut.class, Around.class, Before.class, After.class, AfterReturning.class, AfterThrowing.class
//并把注解信息封装成AspectJAnnotation对象
AspectJAnnotation<?> aspectJAnnotation =
AbstractAspectJAdvisorFactory.findAspectJAnnotationOnMethod(candidateAdviceMethod);
然后看具体实现
@Nullable
protected static AspectJAnnotation<?> findAspectJAnnotationOnMethod(Method method) {
//Pointcut.class, Around.class, Before.class, After.class, AfterReturning.class, AfterThrowing.class
for (Class<?> clazz : ASPECTJ_ANNOTATION_CLASSES) {
//找到Pointcut.class, Around.class, Before.class, After.class, AfterReturning.class, AfterThrowing.class
//注解的方法，并且把注解里面的信息封装成AspectJAnnotation对象
AspectJAnnotation<?> foundAnnotation = findAnnotation(method, (Class<Annotation>) clazz);
if (foundAnnotation != null) {
return foundAnnotation;
}
}
return null;
}
遍历这个属性：ASPECTJ_ANNOTATION_CLASSES，这个属性的值是：
private static final Class<?>[] ASPECTJ_ANNOTATION_CLASSES = new Class<?>[] {
Pointcut.class, Around.class, Before.class, After.class, AfterReturning.class, AfterThrowing.class};
然后这个具体逻辑是这里实现的
AspectJAnnotation<?> foundAnnotation = findAnnotation(method, (Class<Annotation>) clazz);
具体实现的逻辑
@Nullable
private static <A extends Annotation> AspectJAnnotation<A> findAnnotation(Method method, Class<A> toLookFor) {
A result = AnnotationUtils.findAnnotation(method, toLookFor);
if (result != null) {
//把注解里面的信息解析出来，然后包装成AspectJAnnotation对象
return new AspectJAnnotation<>(result);
}
else {
return null;
}
}
回到getPointcut方法
@Nullable
private AspectJExpressionPointcut getPointcut(Method candidateAdviceMethod, Class<?> candidateAspectClass) {
//从候选的增强方法里面 candidateAdviceMethod 找有有注解
//Pointcut.class, Around.class, Before.class, After.class, AfterReturning.class, AfterThrowing.class
//并把注解信息封装成AspectJAnnotation对象
AspectJAnnotation<?> aspectJAnnotation =
AbstractAspectJAdvisorFactory.findAspectJAnnotationOnMethod(candidateAdviceMethod);
if (aspectJAnnotation == null) {
return null;
}
//创建一个PointCut类，并且把前面从注解里面解析的表达式设置进去
AspectJExpressionPointcut ajexp =
new AspectJExpressionPointcut(candidateAspectClass, new String[0], new Class<?>[0]);
ajexp.setExpression(aspectJAnnotation.getPointcutExpression());
if (this.beanFactory != null) {
ajexp.setBeanFactory(this.beanFactory);
}
return ajexp;
}
上面完成了AspectJAnnotation的对象的封装，然后将这个属性放进新建的PointCut类中，并且把前面从注解里面解析的表达式设置进去
//创建一个PointCut类，并且把前面从注解里面解析的表达式设置进去
AspectJExpressionPointcut ajexp =
new AspectJExpressionPointcut(candidateAspectClass, new String[0], new Class<?>[0]);
完成后会return到getAdvisor方法中
@Override
@Nullable
public Advisor getAdvisor(Method candidateAdviceMethod, MetadataAwareAspectInstanceFactory aspectInstanceFactory,
int declarationOrderInAspect, String aspectName) {
validate(aspectInstanceFactory.getAspectMetadata().getAspectClass());
//获取pointCut对象，最重要的是从注解中获取表达式
AspectJExpressionPointcut expressionPointcut = getPointcut(
candidateAdviceMethod, aspectInstanceFactory.getAspectMetadata().getAspectClass());
if (expressionPointcut == null) {
return null;
}
//创建Advisor切面类，这才是真正的切面类，一个切面类里面肯定要有1、pointCut 2、advice
//这里pointCut是expressionPointcut， advice 增强方法是 candidateAdviceMethod
return new InstantiationModelAwarePointcutAdvisorImpl(expressionPointcut, candidateAdviceMethod,
this, aspectInstanceFactory, declarationOrderInAspect, aspectName);
}
在代码走完getPointcut();这个逻辑后就获取到了Pointcut这个要素，还缺少一个advice，于是下面的代码需要完成新建advice并且将这两个属性封装成Advisor
/创建Advisor切面类，这才是真正的切面类，一个切面类里面肯定要有1、pointCut 2、advice
//这里pointCut是expressionPointcut， advice 增强方法是 candidateAdviceMethod
return new InstantiationModelAwarePointcutAdvisorImpl(expressionPointcut, candidateAdviceMethod,
this, aspectInstanceFactory, declarationOrderInAspect, aspectName);
查看这个构造方法
public InstantiationModelAwarePointcutAdvisorImpl(AspectJExpressionPointcut declaredPointcut,
Method aspectJAdviceMethod, AspectJAdvisorFactory aspectJAdvisorFactory,
MetadataAwareAspectInstanceFactory aspectInstanceFactory, int declarationOrder, String aspectName) {
this.declaredPointcut = declaredPointcut;
this.declaringClass = aspectJAdviceMethod.getDeclaringClass();
this.methodName = aspectJAdviceMethod.getName();
this.parameterTypes = aspectJAdviceMethod.getParameterTypes();
this.aspectJAdviceMethod = aspectJAdviceMethod;
this.aspectJAdvisorFactory = aspectJAdvisorFactory;
this.aspectInstanceFactory = aspectInstanceFactory;
this.declarationOrder = declarationOrder;
this.aspectName = aspectName;
if (aspectInstanceFactory.getAspectMetadata().isLazilyInstantiated()) {
// Static part of the pointcut is a lazy type.
Pointcut preInstantiationPointcut = Pointcuts.union(
aspectInstanceFactory.getAspectMetadata().getPerClausePointcut(), this.declaredPointcut);
// Make it dynamic: must mutate from pre-instantiation to post-instantiation state.
// If it's not a dynamic pointcut, it may be optimized out
// by the Spring AOP infrastructure after the first evaluation.
this.pointcut = new PerTargetInstantiationModelPointcut(
this.declaredPointcut, preInstantiationPointcut, aspectInstanceFactory);
this.lazy = true;
}
else {
// A singleton aspect.
this.pointcut = this.declaredPointcut;
this.lazy = false;
//这个方法重点看看，创建advice对象
this.instantiatedAdvice = instantiateAdvice(this.declaredPointcut);
}
}
第一段代码将point的值设置进去了
this.declaredPointcut = declaredPointcut;
然后最后一句代码完成了创建advice的重任
//这个方法重点看看，创建advice对象
this.instantiatedAdvice = instantiateAdvice(this.declaredPointcut);
private Advice instantiateAdvice(AspectJExpressionPointcut pointcut) {
//创建Advice对象
Advice advice = this.aspectJAdvisorFactory.getAdvice(this.aspectJAdviceMethod, pointcut,
this.aspectInstanceFactory, this.declarationOrder, this.aspectName);
return (advice != null ? advice : EMPTY_ADVICE);
}
具体查看getAdvice(),这里会将不同的注解类型封装成不同的子类，后面调用的时候会使用到的
@Override
@Nullable
public Advice getAdvice(Method candidateAdviceMethod, AspectJExpressionPointcut expressionPointcut,
MetadataAwareAspectInstanceFactory aspectInstanceFactory, int declarationOrder, String aspectName) {
//获取有@Aspect注解的类
Class<?> candidateAspectClass = aspectInstanceFactory.getAspectMetadata().getAspectClass();
validate(candidateAspectClass);
//找到candidateAdviceMethod方法上面的注解，并且包装成AspectJAnnotation对象，这个对象中就有注解类型
AspectJAnnotation<?> aspectJAnnotation =
AbstractAspectJAdvisorFactory.findAspectJAnnotationOnMethod(candidateAdviceMethod);
if (aspectJAnnotation == null) {
return null;
}
// If we get here, we know we have an AspectJ method.
// Check that it's an AspectJ-annotated class
if (!isAspect(candidateAspectClass)) {
throw new AopConfigException("Advice must be declared inside an aspect type: " +
"Offending method '" + candidateAdviceMethod + "' in class [" +
candidateAspectClass.getName() + "]");
}
if (logger.isDebugEnabled()) {
logger.debug("Found AspectJ method: " + candidateAdviceMethod);
}
AbstractAspectJAdvice springAdvice;
//根据不同的注解类型创建不同的advice类实例
switch (aspectJAnnotation.getAnnotationType()) {
case AtPointcut:
if (logger.isDebugEnabled()) {
logger.debug("Processing pointcut '" + candidateAdviceMethod.getName() + "'");
}
return null;
case AtAround:
//实现了MethodInterceptor接口
springAdvice = new AspectJAroundAdvice(
candidateAdviceMethod, expressionPointcut, aspectInstanceFactory);
break;
case AtBefore:
//实现了MethodBeforeAdvice接口，没有实现MethodInterceptor接口
springAdvice = new AspectJMethodBeforeAdvice(
candidateAdviceMethod, expressionPointcut, aspectInstanceFactory);
break;
case AtAfter:
//实现了MethodInterceptor接口
springAdvice = new AspectJAfterAdvice(
candidateAdviceMethod, expressionPointcut, aspectInstanceFactory);
break;
case AtAfterReturning:
//实现了AfterReturningAdvice接口，没有实现MethodInterceptor接口
springAdvice = new AspectJAfterReturningAdvice(
candidateAdviceMethod, expressionPointcut, aspectInstanceFactory);
AfterReturning afterReturningAnnotation = (AfterReturning) aspectJAnnotation.getAnnotation();
if (StringUtils.hasText(afterReturningAnnotation.returning())) {
springAdvice.setReturningName(afterReturningAnnotation.returning());
}
break;
case AtAfterThrowing:
//实现了MethodInterceptor接口
springAdvice = new AspectJAfterThrowingAdvice(
candidateAdviceMethod, expressionPointcut, aspectInstanceFactory);
AfterThrowing afterThrowingAnnotation = (AfterThrowing) aspectJAnnotation.getAnnotation();
if (StringUtils.hasText(afterThrowingAnnotation.throwing())) {
springAdvice.setThrowingName(afterThrowingAnnotation.throwing());
}
break;
default:
throw new UnsupportedOperationException(
"Unsupported advice type on method: " + candidateAdviceMethod);
}
// Now to configure the advice...
springAdvice.setAspectName(aspectName);
springAdvice.setDeclarationOrder(declarationOrder);
//获取注解中的argNames属性参数名称
String[] argNames = this.parameterNameDiscoverer.getParameterNames(candidateAdviceMethod);
if (argNames != null) {
springAdvice.setArgumentNamesFromStringArray(argNames);
}
//计算argNames和类型的对应关系
springAdvice.calculateArgumentBindings();
return springAdvice;
}
然后这样就基本完成了advisor的创建，回到getAdvisors这个方法中
@Override
public List<Advisor> getAdvisors(MetadataAwareAspectInstanceFactory aspectInstanceFactory) {
//从工厂中获取有@Aspect注解的类Class
Class<?> aspectClass = aspectInstanceFactory.getAspectMetadata().getAspectClass();
//从工厂中获取有@Aspect注解的类的名称
String aspectName = aspectInstanceFactory.getAspectMetadata().getAspectName();
validate(aspectClass);
//创建工厂的装饰类，获取实例只会获取一次
// We need to wrap the MetadataAwareAspectInstanceFactory with a decorator
// so that it will only instantiate once.
MetadataAwareAspectInstanceFactory lazySingletonAspectInstanceFactory =
new LazySingletonAspectInstanceFactoryDecorator(aspectInstanceFactory);
List<Advisor> advisors = new ArrayList<>();
//这里循环没有@Pointcut注解的方法
for (Method method : getAdvisorMethods(aspectClass)) {
// Prior to Spring Framework 5.2.7, advisors.size() was supplied as the declarationOrderInAspect
// to getAdvisor(...) to represent the "current position" in the declared methods list.
// However, since Java 7 the "current position" is not valid since the JDK no longer
// returns declared methods in the order in which they are declared in the source code.
// Thus, we now hard code the declarationOrderInAspect to 0 for all advice methods
// discovered via reflection in order to support reliable advice ordering across JVM launches.
// Specifically, a value of 0 aligns with the default value used in
// AspectJPrecedenceComparator.getAspectDeclarationOrder(Advisor).
//非常重要重点看看，重要程度 5
Advisor advisor = getAdvisor(method, lazySingletonAspectInstanceFactory, 0, aspectName);
if (advisor != null) {
advisors.add(advisor);
}
}
// If it's a per target aspect, emit the dummy instantiating aspect.
if (!advisors.isEmpty() && lazySingletonAspectInstanceFactory.getAspectMetadata().isLazilyInstantiated()) {
Advisor instantiationAdvisor = new SyntheticInstantiationAdvisor(lazySingletonAspectInstanceFactory);
advisors.add(0, instantiationAdvisor);
}
//判断属性上是否有引介注解
// Find introduction fields.
for (Field field : aspectClass.getDeclaredFields()) {
//判断属性上是否有DeclareParents注解，如果有返回切面
Advisor advisor = getDeclareParentsAdvisor(field);
if (advisor != null) {
advisors.add(advisor);
}
}
return advisors;
}
根据方法上的类型判断后，收集到advisor属性后继续返回
返回到findEligibleAdvisors这个方法后，上面的代码就算是完成了@Aspectj注解信息的收集，然后现在要开始匹配属性了
protected List<Advisor> findEligibleAdvisors(Class<?> beanClass, String beanName) {
//找到候选的切面,其实就是一个寻找有@Aspectj注解的过程，把工程中所有有这个注解的类封装成Advisor返回
// 调用子类的方法AnnotationAwareAspectJAutoProxyCreator
List<Advisor> candidateAdvisors = findCandidateAdvisors();
//判断候选的切面是否作用在当前beanClass上面，就是一个匹配过程。。现在就是一个匹配
List<Advisor> eligibleAdvisors = findAdvisorsThatCanApply(candidateAdvisors, beanClass, beanName);
//针对@Aspect注解切面添加了一个默认的切面 DefaultPointcutAdvisor
extendAdvisors(eligibleAdvisors);
if (!eligibleAdvisors.isEmpty()) {
//对有@Order@Priority进行排序
eligibleAdvisors = sortAdvisors(eligibleAdvisors);
}
return eligibleAdvisors;
}
具体这里实现
//判断候选的切面是否作用在当前beanClass上面，就是一个匹配过程。。现在就是一个匹配
List<Advisor> eligibleAdvisors = findAdvisorsThatCanApply(candidateAdvisors, beanClass, beanName);
protected List<Advisor> findAdvisorsThatCanApply(
List<Advisor> candidateAdvisors, Class<?> beanClass, String beanName) {
ProxyCreationContext.setCurrentProxiedBeanName(beanName);
try {
//看看当前类是否在这些切面的pointCut中..掉类和方法的match过程
return AopUtils.findAdvisorsThatCanApply(candidateAdvisors, beanClass);
}
finally {
ProxyCreationContext.setCurrentProxiedBeanName(null);
}
}
两次match：class和method
public static List<Advisor> findAdvisorsThatCanApply(List<Advisor> candidateAdvisors, Class<?> clazz) {
if (candidateAdvisors.isEmpty()) {
return candidateAdvisors;
}
List<Advisor> eligibleAdvisors = new ArrayList<>();
for (Advisor candidate : candidateAdvisors) {
//如果是引介切面并且匹配
if (candidate instanceof IntroductionAdvisor && canApply(candidate, clazz)) {
eligibleAdvisors.add(candidate);
}
}
boolean hasIntroductions = !eligibleAdvisors.isEmpty();
//调用pointCut中的ClassFilter 和methodMatcher的match方法的过程
for (Advisor candidate : candidateAdvisors) {
if (candidate instanceof IntroductionAdvisor) {
// already processed
continue;
}
if (canApply(candidate, clazz, hasIntroductions)) {
eligibleAdvisors.add(candidate);
}
}
return eligibleAdvisors;
}
只需要看canApply这个方法的实现逻辑
public static boolean canApply(Advisor advisor, Class<?> targetClass, boolean hasIntroductions) {
if (advisor instanceof IntroductionAdvisor) {
return ((IntroductionAdvisor) advisor).getClassFilter().matches(targetClass);
}
else if (advisor instanceof PointcutAdvisor) {
PointcutAdvisor pca = (PointcutAdvisor) advisor;
return canApply(pca.getPointcut(), targetClass, hasIntroductions);
}
else {
// It doesn't have a pointcut so we assume it applies.
return true;
}
}
public static boolean canApply(Pointcut pc, Class<?> targetClass, boolean hasIntroductions) {
Assert.notNull(pc, "Pointcut must not be null");
//调用ClassFilter的matches方法，判断类是否匹配
if (!pc.getClassFilter().matches(targetClass)) {
return false;
}
MethodMatcher methodMatcher = pc.getMethodMatcher();
if (methodMatcher == MethodMatcher.TRUE) {
// No need to iterate the methods if we're matching any method anyway...
return true;
}
IntroductionAwareMethodMatcher introductionAwareMethodMatcher = null;
if (methodMatcher instanceof IntroductionAwareMethodMatcher) {
introductionAwareMethodMatcher = (IntroductionAwareMethodMatcher) methodMatcher;
}
Set<Class<?>> classes = new LinkedHashSet<>();
if (!Proxy.isProxyClass(targetClass)) {
classes.add(ClassUtils.getUserClass(targetClass));
}
classes.addAll(ClassUtils.getAllInterfacesForClassAsSet(targetClass));
//判断类中方法是否匹配，，有些可能是方法上面有注解的拦截，所以需要判断方法是否匹配
for (Class<?> clazz : classes) {
Method[] methods = ReflectionUtils.getAllDeclaredMethods(clazz);
for (Method method : methods) {
if (introductionAwareMethodMatcher != null ?
introductionAwareMethodMatcher.matches(method, targetClass, hasIntroductions) :
methodMatcher.matches(method, targetClass)) {
return true;
}
}
}
return false;
}